Purchase decision-making is modulated by vestibular stimulation

Purchases are driven by consumers’ product preferences and price considerations. Using caloric vestibular stimulation (CVS), we investigated the role of vestibular-affective circuits in purchase decision-making. CVS is an effective noninvasive brain stimulation method, which activates vestibular and overlapping emotional circuits (e.g., the insular cortex and the anterior cingulate cortex (ACC)). Subjects were exposed to CVS and sham stimulation while they performed two purchase decision-making tasks. In Experiment 1 subjects had to decide whether to purchase or not. CVS significantly reduced probability of buying a product. In Experiment 2 subjects had to rate desirability of the products and willingness to pay (WTP) while they were exposed to CVS and sham stimulation. CVS modulated desirability of the products but not WTP. The results suggest that CVS interfered with emotional circuits and thus attenuated the pleasant and rewarding effect of acquisition, which in turn reduced purchase probability. The present findings contribute to the rapidly growing literature on the neural basis of purchase decision-making.

Metabotropic glutamate receptor 5 binding in patients with obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a disabling, mostly chronic, psychiatric condition with significant social and economic impairments and is a major public health issue. However, numerous patients are resistant to currently available pharmacological and psychological interventions. Given that recent animal studies and magnetic resonance spectroscopy research points to glutamate dysfunction in OCD, we investigated the metabotropic glutamate receptor 5 (mGluR5) in patients with OCD and healthy controls. We determined mGluR5 distribution volume ratio (DVR) in the brain of ten patients with OCD and ten healthy controls by using [11C]ABP688 positron-emission tomography. As a clinical measure of OCD severity, the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) was employed. We found no significant global difference in mGluR5 DVR between patients with OCD and healthy controls. We did, however, observe significant positive correlations between the Y-BOCS obsession sub-score and mGluR5 DVR in the cortico-striatal-thalamo-cortical brain circuit, including regions of the amygdala, anterior cingulate cortex, and medial orbitofrontal cortex (Spearman's ρ's⩾ = 0.68, p < 0.05). These results suggest that obsessions in particular might have an underlying glutamatergic pathology related to mGluR5. The research indicates that the development of metabotropic glutamate agents would be useful as a new treatment for OCD.

Prefrontal GABA and glutathione imbalance in posttraumatic stress disorder: Preliminary findings.

Although posttraumatic stress disorder (PTSD) is associated with a variety of structural and functional brain changes, the molecular pathophysiological mechanisms underlying these macroscopic alterations are unknown. Recent studies support the existence of an altered excitation-inhibition balance in PTSD. Further, there is preliminary evidence from blood-sample studies suggesting heightened oxidative stress in PTSD, potentially leading to neural damage through excessive brain levels of free radicals. In this study we investigated PTSD (n=12) and non-PTSD participants (n=17) using single-voxel proton magnetic resonance spectroscopy (MRS) in dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex (ACC). We found significantly higher levels of γ-amino butyric acid (GABA) (a primary inhibitory neurotransmitter) and glutathione (a marker for neuronal oxidative stress) in PTSD participants. Atypically high prefrontal inhibition as well as oxidative stress may be involved in the pathogenesis of PTSD.

Interhemispheric cerebral blood flow balance during recovery of motor hand function after ischemic stroke - a longitudinal MRI study using arterial spin labeling perfusion

BACKGROUND Unilateral ischemic stroke disrupts the well balanced interactions within bilateral cortical networks. Restitution of interhemispheric balance is thought to contribute to post-stroke recovery. Longitudinal measurements of cerebral blood flow (CBF) changes might act as surrogate marker for this process. OBJECTIVE To quantify longitudinal CBF changes using arterial spin labeling MRI (ASL) and interhemispheric balance within the cortical sensorimotor network and to assess their relationship with motor hand function recovery. METHODS Longitudinal CBF data were acquired in 23 patients at 3 and 9 months after cortical sensorimotor stroke and in 20 healthy controls using pulsed ASL. Recovery of grip force and manual dexterity was assessed with tasks requiring power and precision grips. Voxel-based analysis was performed to identify areas of significant CBF change. Region-of-interest analyses were used to quantify the interhemispheric balance across nodes of the cortical sensorimotor network. RESULTS Dexterity was more affected, and recovered at a slower pace than grip force. In patients with successful recovery of dexterous hand function, CBF decreased over time in the contralesional supplementary motor area, paralimbic anterior cingulate cortex and superior precuneus, and interhemispheric balance returned to healthy control levels. In contrast, patients with poor recovery presented with sustained hypoperfusion in the sensorimotor cortices encompassing the ischemic tissue, and CBF remained lateralized to the contralesional hemisphere. CONCLUSIONS Sustained perfusion imbalance within the cortical sensorimotor network, as measured with task-unrelated ASL, is associated with poor recovery of dexterous hand function after stroke. CBF at rest might be used to monitor recovery and gain prognostic information.

Neural patterns underlying social comparisons of personal performance

Humans often evaluate their abilities by comparing their personal performance with that of others. For this process, it is critical whether the comparison turns out in one's favor or against it. Here, we investigate how social comparisons of performance are encoded and integrated on the neural level. We collected functional magnetic resonance images while subjects answered questions in a knowledge quiz that was related to their profession. After each question, subjects received a feedback about their personal performance, followed by a feedback about the performance of a reference group who had been quizzed beforehand. Based on the subjects' personal performance, we divided trials in downward and upward comparisons. We found that upward comparisons correlated with activity in the dorsolateral prefrontal cortex and the anterior insula. Downward comparisons were associated with increased activation in the ventral striatum (VS), the medial orbitofrontal cortex and the ventral anterior cingulate cortex (ACC). The extent to which subjects outperformed the reference group modulated the activity in the VS and in the dorsal ACC. We suggest that the co-activation of the VS and the dorsal ACC contributes to the integration of downward comparisons into the evaluation of personal performance.

Neural correlates of anticipation risk reflect risk preferences

Individual risk preferences have a large influence on decisions, such as financial investments, career and health choices, or gambling. Decision making under risk has been studied both behaviorally and on a neural level. It remains unclear, however, how risk attitudes are encoded and integrated with choice. Here, we investigate how risk preferences are reflected in neural regions known to process risk. We collected functional magnetic resonance images of 56 human subjects during a gambling task (Preuschoff et al., 2006). Subjects were grouped into risk averters and risk seekers according to the risk preferences they revealed in a separate lottery task. We found that during the anticipation of high-risk gambles, risk averters show stronger responses in ventral striatum and anterior insula compared to risk seekers. In addition, risk prediction error signals in anterior insula, inferior frontal gyrus, and anterior cingulate indicate that risk averters do not dissociate properly between gambles that are more or less risky than expected. We suggest this may result in a general overestimation of prospective risk and lead to risk avoidance behavior. This is the first study to show that behavioral risk preferences are reflected in the passive evaluation of risky situations. The results have implications on public policies in the financial and health domain.

Induction of Fear by Intraoperative Stimulation During Awake Craniotomy: Case Presentation and Systematic Review of the Literature.

PURPOSE A case is presented and a systematic review of the literature is provided to update our current knowledge of induction of fear by cortical stimulation. METHODS We present a case of refractory epilepsy associated with a lesion where fear could be induced by intraoperative electrical stimulation of the posterior inner part of the superior temporal gyrus. We performed a systematic review of the literature using PubMed with the key words "epilepsy AND emotion", "cortical stimulation AND emotion," and "human brain stimulation AND behavior". RESULTS Intraoperative cortical stimulation of the inner part of the posterior superior temporal gyrus reliably induced fear and progressive screaming behavior. Stimulation through subdural grid electrodes did not induce this phenomenon. A systematic review of the literature identified fear induction by stimulation of different widespread cortical areas including the temporal pole, the insula, and the anterior cingulate cortex. The posterior part of the superior temporal gyrus has so far not been associated with fear induction after electrical stimulation. CONCLUSION Although our observation suggests that this area of the brain could be part of a network involved in the elicitation of fear, dysfunction of this network induced by epilepsy could also explain the observed phenomenon. Electrophysiologic and imaging studies must be conducted to improve our understanding of the cortical networks forming the neuroanatomical substrate of higher brain functions and experiences such as fear.

Dysfunction of Cortical Dendritic Integration in Neuropathic Pain Reversed by Serotoninergic Neuromodulation

Neuropathic pain is caused by long-term modifications of neuronal function in the peripheral nervous system, the spinal cord, and supraspinal areas. Although functional changes in the forebrain are thought to contribute to the development of persistent pain, their significance and precise subcellular nature remain unexplored. Using somatic and dendritic whole-cell patch-clamp recordings from neurons in the anterior cingulate cortex, we discovered that sciatic nerve injury caused an activity-dependent dysfunction of hyperpolarization-activated cyclic nucleotide-regulated (HCN) channels in the dendrites of layer 5 pyramidal neurons resulting in enhanced integration of excitatory postsynaptic inputs and increased neuronal firing. Specific activation of the serotonin receptor type 7 (5-HT7R) alleviated the lesion-induced pathology by increasing HCN channel function, restoring normal dendritic integration, and reducing mechanical pain hypersensitivity in nerve-injured animals in vivo. Thus, serotoninergic neuromodulation at the forebrain level can reverse the dendritic dysfunction induced by neuropathic pain and may represent a potential therapeutical target.

Violence-related PTSD and neural activation when seeing emotionally charged male-female interactions.

Post-traumatic stress disorder (PTSD) is a disorder that involves impaired regulation of the fear response to traumatic reminders. This study tested how women with male-perpetrated interpersonal violence-related PTSD (IPV-PTSD) differed in their brain activation from healthy controls (HC) when exposed to scenes of male-female interaction of differing emotional content. Sixteen women with symptoms of IPV-PTSD and 19 HC participated in this study. During magnetic resonance imaging, participants watched a stimulus protocol of 23 different 20 s silent epochs of male-female interactions taken from feature films, which were neutral, menacing or prosocial. IPV-PTSD participants compared with HC showed (i) greater dorsomedial prefrontal cortex (dmPFC) and dorsolateral prefrontal cortex (dlPFC) activation in response to menacing vs prosocial scenes and (ii) greater anterior cingulate cortex (ACC), right hippocampus activation and lower ventromedial prefrontal cortex (vmPFC) activty in response to emotional vs neutral scenes. The fact that IPV-PTSD participants compared with HC showed lower activity of the ventral ACC during emotionally charged scenes regardless of the valence of the scenes suggests that impaired social perception among IPV-PTSD patients transcends menacing contexts and generalizes to a wider variety of emotionally charged male-female interactions.

Visual avoidance in phobia: particularities in neural activity, autonomic responding, and cognitive risk evaluations.

We investigated the neural mechanisms and the autonomic and cognitive responses associated with visual avoidance behavior in spider phobia. Spider phobic and control participants imagined visiting different forest locations with the possibility of encountering spiders, snakes, or birds (neutral reference category). In each experimental trial, participants saw a picture of a forest location followed by a picture of a spider, snake, or bird, and then rated their personal risk of encountering these animals in this context, as well as their fear. The greater the visual avoidance of spiders that a phobic participant demonstrated (as measured by eye tracking), the higher were her autonomic arousal and neural activity in the amygdala, orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), and precuneus at picture onset. Visual avoidance of spiders in phobics also went hand in hand with subsequently reduced cognitive risk of encounters. Control participants, in contrast, displayed a positive relationship between gaze duration toward spiders, on the one hand, and autonomic responding, as well as OFC, ACC, and precuneus activity, on the other hand. In addition, they showed reduced encounter risk estimates when they looked longer at the animal pictures. Our data are consistent with the idea that one reason for phobics to avoid phobic information may be grounded in heightened activity in the fear circuit, which signals potential threat. Because of the absence of alternative efficient regulation strategies, visual avoidance may then function to down-regulate cognitive risk evaluations for threatening information about the phobic stimuli. Control participants, in contrast, may be characterized by a different coping style, whereby paying visual attention to potentially threatening information may help them to actively down-regulate cognitive evaluations of risk.

Altered directed functional connectivity in temporal lobe epilepsy in the absence of interictal spikes: A high density EEG study.

OBJECTIVE In patients with epilepsy, seizure relapse and behavioral impairments can be observed despite the absence of interictal epileptiform discharges (IEDs). Therefore, the characterization of pathologic networks when IEDs are not present could have an important clinical value. Using Granger-causal modeling, we investigated whether directed functional connectivity was altered in electroencephalography (EEG) epochs free of IED in left and right temporal lobe epilepsy (LTLE and RTLE) compared to healthy controls. METHODS Twenty LTLE, 20 RTLE, and 20 healthy controls underwent a resting-state high-density EEG recording. Source activity was obtained for 82 regions of interest (ROIs) using an individual head model and a distributed linear inverse solution. Granger-causal modeling was applied to the source signals of all ROIs. The directed functional connectivity results were compared between groups and correlated with clinical parameters (duration of the disease, age of onset, age, and learning and mood impairments). RESULTS We found that: (1) patients had significantly reduced connectivity from regions concordant with the default-mode network; (2) there was a different network pattern in patients versus controls: the strongest connections arose from the ipsilateral hippocampus in patients and from the posterior cingulate cortex in controls; (3) longer disease duration was associated with lower driving from contralateral and ipsilateral mediolimbic regions in RTLE; (4) aging was associated with a lower driving from regions in or close to the piriform cortex only in patients; and (5) outflow from the anterior cingulate cortex was lower in patients with learning deficits or depression compared to patients without impairments and to controls. SIGNIFICANCE Resting-state network reorganization in the absence of IEDs strengthens the view of chronic and progressive network changes in TLE. These resting-state connectivity alterations could constitute an important biomarker of TLE, and hold promise for using EEG recordings without IEDs for diagnosis or prognosis of this disorder.

Structural brain correlates of defective gesture performance in schizophrenia

INTRODUCTION The neural correlates of impaired performance of gestures are currently unclear. Lesion studies showed variable involvement of the ventro-dorsal stream particularly left inferior frontal gyrus (IFG) in gesture performance on command. However, findings cannot be easily generalized as lesions may be biased by the architecture of vascular supply and involve brain areas beyond the critical region. The neuropsychiatric syndrome of schizophrenia shares apraxic-like errors and altered brain structure without macroanatomic lesions. Schizophrenia may therefore qualify as a model disorder to test neural correlates of gesture impairments. METHODS We included 45 schizophrenia patients and 44 healthy controls in the study to investigate the structural brain correlates of defective gesturing in schizophrenia using voxel based morphometry. Gestures were tested in two domains: meaningful gestures (transitive and intransitive) on verbal command and imitation of meaningless gestures. Cut-off scores were used to separate patients with deficits, patients without deficits and controls. Group differences in gray matter (GM) volume were explored in an ANCOVA. RESULTS Patients performed poorer than controls in each gesture category (p < .001). Patients with deficits in producing meaningful gestures on command had reduced GM predominantly in left IFG, with additional involvement of right insula and anterior cingulate cortex. Patients with deficits differed from patients without deficits in right insula, inferior parietal lobe (IPL) and superior temporal gyrus. CONCLUSIONS Impaired performance of meaningful gestures on command was linked to volume loss predominantly in the praxis network in schizophrenia. Thus, the behavioral similarities between apraxia and schizophrenia are paralleled by structural alterations. However, few associations between behavioral impairment and structural brain alterations appear specific to schizophrenia.

Surgical treatment of upper, middle and lower cervical injuries and non-unions by anterior procedures

The goals of any treatment of cervical spine injuries are: return to maximum functional ability, minimum of residual pain, decrease of any neurological deficit, minimum of residual deformity and prevention of further disability. The advantages of surgical treatment are the ability to reach optimal reduction, immediate stability, direct decompression of the cord and the exiting roots, the need for only minimum external fixation, the possibility for early mobilisation and clearly decreased nursing problems. There are some reasons why those goals can be reached better by anterior surgery. Usually the bony compression of the cord and roots comes from the front therefore anterior decompression is usually the procedure of choice. Also, the anterior stabilisation with a plate is usually simpler than a posterior instrumentation. It needs to be stressed that closed reduction by traction can align the fractured spine and indirectly decompress the neural structures in about 70%. The necessary weight is 2.5 kg per level of injury. In the upper cervical spine, the odontoid fracture type 2 is an indication for anterior surgery by direct screw fixation. Joint C1/C2 dislocations or fractures or certain odontoid fractures can be treated with a fusion of the C1/C2 joint by anterior transarticular screw fixation. In the lower and middle cervical spine, anterior plating combined with iliac crest or fibular strut graft is the procedure of choice, however, a solid graft can also be replaced by filled solid or expandable vertebral cages. The complication of this surgery is low, when properly executed and anterior surgery may only be contra-indicated in case of a significant lesion or locked joints.

Left atrial myxoma attached to the anterior mitral leaflet with symptoms suggestive of infective endocarditis

The case of a 55-year-old woman is presented, whose clinical signs were initially suggestive of infective endocarditis. Transthoracic echocardiography (TTE) provided the diagnosis of a large left atrial myxoma attached to the anterior mitral leaflet. Perioperative transesophageal echocardiography (TEE) confirmed preoperative findings and assisted the surgical team in the assessment of tumour size, area of attachment, and mobility. Following tumour resection, TEE demonstrated residual moderate mitral valve regurgitation, which resulted in a change of surgical strategy. This report reinforces the importance of intraoperative TEE to facilitate and optimize surgical and anaesthesiological management of patients presenting with non-specific cardiorespiratory symptoms.

Posterior versus anterior circulation strokes: comparison of clinical, radiological and outcome characteristics

Physicians treating patients with posterior circulation strokes (PCS) tended to debate more on whether or not to introduce anticoagulation rather than performing investigations to identify stroke aetiology, as in patients with anterior circulation strokes (ACS). Recent findings suggest that stroke aetiologies of PCS and ACS are more alike than dissimilar, suggesting that PCS deserve the same investigations as ACS. The characteristics and current diagnostic evaluation between patients with PCS and ACS were compared.